Questions and Answers

Suburban Has No Spark Q. Is there any way to determine if my engine has "jumped" a tooth on the timing chain other than to disassemble the front of the engine? I have a 1986 HEI distributor Chevy Suburban with a 350 4bbl carburetor automatic transmission. I was driving down the road at 45 mph and let off the gas to slow down, entering a 35 mph zone, and without any sound or other abnormal occurrence the car no longer responded to the gas pedal being pushed down.

I coasted to the side of the road and have been unable to restart the engine since. I replaced with new all the fuses, the distributor (coil pick up, module, resistor), rotor, cap, coil, wires, plugs, and a check to see that I have power going into the cap. The engine turns over well, the distributor rotates well, but the spark coming from the plugs is weak and sometimes non existent, I can't think of anything else other then the timing chain? If the timing chain had jumped a tooth would it account for the weak spark?

Thanks,
Patrick

A. It looks like you replaced all the ignition system parts that could possibly cause the problem. With that done, it is logical to assume that the problem is in the wiring. If the timing had jumped a tooth, you would still get spark although at the wrong time.

You can check the base timing easily enough. Remove number one spark plug and turn the engine over by hand until the piston is on TDC on the compression stroke. With the piston on TDC the timing mark should be on 0° and the rotor should be pointing at the number one tower on the distributor. You can pop off the valve cover and look to see if the valves for number one cylinder are completely closed also.

With the key on and cranking the engine, check for voltage at the "BAT" terminal of the distributor. It should be at least 8 volts. If not, you have a problem between the ignition switch and the distributor.

The other most likely problem is with the pick up coil in the distributor. Disconnect the pick up coil wires from the module. Stick a spark plug in the end of the coil wire. With the key on connect a test light to the "BAT" terminal and tap the "G" (small) terminal of the module. If you get a spark, then the pick up coil is bad. If not, the module ground is bad.

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